Genetic lesions affecting epigenetic regulators are frequent in myelodysplastic syndromes (MDS). Polycomb proteins are key epigenetic regulators of differentiation and stemness that act as two multimeric complexes termed polycomb repressive complexes 1 and 2, PRC1 and PRC2, respectively. While components and regulators of PRC2 such as ASXL1 and EZH2 are frequently mutated in MDS and AML, little is known about the role of PRC1. To analyze the role of PRC1, we have taken a functional approach testing PRC1 components in loss- and gain-of-function experiments that we found overexpressed in advanced MDS patients or dynamically expressed during normal hematopoiesis. This approach allowed us to identify the enzymatically active component RING1A as the key PRC1 component in hematopoietic stem cells and MDS. Specifically, we found that RING1A is expressed in CD34

ABO blood group A transferases catalyze the biosynthesis of FORS blood group FORS1 antigen upon deletion of exon 3 or 4.

Blood Adv26 Des 2017, 1(27)2756-2766. Epub 20 Des 2017

Evolutionarily related ABO and GBGT1 genes encode, respectively, A and B glycosyltransferases (AT and BT) and Forssman glycolipid synthase (FS), which catalyze the biosynthesis of A and B, and Forssman (FORS1) oligosaccharide antigens responsible for the ABO and FORS blood group systems. Humans are a Forssman antigen-negative species; however, rare individuals with Apae phenotype express FORS1 on their red blood cells. We previously demonstrated that the replacement of the LeuGlyGly tripeptide sequence at codons 266 to 268 of human AT with GBGT1-encoded FS-specific GlyGlyAla enabled the enzyme to produce FORS1 antigen, although the FS activity was weak. We searched for additional molecular mechanisms that might allow human AT to express FORS1. A variety of derivative expression constructs of human AT were prepared. DNA was transfected into COS1 (B3GALNT1) cells, and cell-surface expression of FORS1 was immunologically monitored. To our surprise, the deletion of exon 3 or 4, but not of exon 2 or 5, of human AT transcripts bestowed moderate FS activity, indicating that the A allele is inherently capable of producing a protein with FS activity. Because RNA splicing is frequently altered in cancer, this mechanism may explain, at least partially, the appearance of FORS1 in human cancer. Furthermore, strong FS activity was attained, in addition to AT and BT activities, by cointroducing 1 of those deletions and the GlyGlyAla substitution, possibly by the synergistic effects of altered intra-Golgi localization/conformation by the former and modified enzyme specificity by the latter.

Hereditary hyperferritinaemia-cataract syndrome (HHCS) is a rare disorder usually caused by heterozygous mutations in the iron-responsive element (IRE) in the 5' untranslated region (5'UTR) of the L-ferritin gene (FTL), disturbing the binding of iron regulatory proteins (IRPs) and the post-transcriptional regulation of ferritin expression. Here, the proband of a consanguineous family displayed moderate bilateral cataracts and elevated serum ferritin in the absence of iron overload. The parents and siblings showed variable degrees of mild bilateral cataracts combined with elevated levels of circulating ferritin. Sequencing of FTL identified a novel 5'UTR mutation c.-151A > G, also named "Ghent +49A > G". The zygosity of the mutation, occurring in homozygous and heterozygous state in the proband and other affected family members respectively, correlated well with severity of ophthalmological and hematological manifestations. The substitution is expected to impair the secondary structure of the upper IRE stem. Functional characterization of +49A > G by electrophoretic mobility shift assays demonstrated a reduced binding affinity for IRP1 compared to the wild-type IRE of FTL. Overall, we have expanded the repertoire of deleterious biallelic FTL IRE mutations in HHCS with this novel +49A > G mutation, the zygosity of which correlated well with the disease expression.

Clinical and biological significance of isolated Y chromosome loss in myelodysplastic syndromes and chronic myelomonocytic leukemia. A report from the Spanish MDS Group.

Leuk. Res.Des 2017, 6385-89. Epub 28 Oct 2017

Isolate loss of chromosome Y (-Y) in myelodysplastic syndromes (MDS) is associated to a better outcome but it is also well described as an age-related phenomenon. In this study we aimed to analyze the prognostic impact of -Y in the context of the IPSS-R cytogenetic classification, evaluate the clinical significance of the percentage of metaphases with isolated -Y, and test whether finding -Y may predispose to over-diagnose MDS in patients with borderline morphological features. We evaluated 3581 male patients from the Spanish MDS Registry with a diagnosis of MDS or chronic myelomonocytic leukemia (CMML). -Y was identified in 177 patients (4.9%). Compared with the 2246 male patients with normal karyotype, -Y group showed a reduced risk of leukemic transformation that did not translate into a survival advantage. The overall survival and the risk of leukemic transformation were not influenced by the percentage of metaphases with -Y. The -Y group was not enriched in patients with minor morphologic traits of dysplasia, suggesting that the better outcome in the -Y group cannot be explained by enrichment in cases misdiagnosed as MDS. In conclusion, our results support the current recommendation of classifying patients with -Y within the very good risk category of the IPSS-R for MDS and rule out a selection bias as a possible explanation of this better outcome. An analysis of the molecular basis of MDS with isolated -Y would be of interest as it may provide a biological basis of protection against progression to acute leukemia.

Prediction of peripheral neuropathy in multiple myeloma patients receiving bortezomib and thalidomide: a genetic study based on a single nucleotide polymorphism array.

Hematol OncolDes 2017, 35(4)746-751. Epub 8 Set 2016

Bortezomib- and thalidomide-based therapies have significantly contributed to improved survival of multiple myeloma (MM) patients. However, treatment-induced peripheral neuropathy (TiPN) is a common adverse event associated with them. Risk factors for TiPN in MM patients include advanced age, prior neuropathy, and other drugs, but there are conflicting results about the role of genetics in predicting the risk of TiPN. Thus, we carried out a genome-wide association study based on more than 300 000 exome single nucleotide polymorphisms in 172 MM patients receiving therapy involving bortezomib and thalidomide. We compared patients developing and not developing TiPN under similar treatment conditions (GEM05MAS65, NCT00443235). The highest-ranking single nucleotide polymorphism was rs45443101, located in the PLCG2 gene, but no significant differences were found after multiple comparison correction (adjusted P = .1708). Prediction analyses, cytoband enrichment, and pathway analyses were also performed, but none yielded any significant findings. A copy number approach was also explored, but this gave no significant results either. In summary, our study did not find a consistent genetic component associated with TiPN under bortezomib and thalidomide therapies that could be used for prediction, which makes clinical judgment essential in the practical management of MM treatment.

HoxA9 is an evolutionarily conserved homeobox gene implicated in embryo development. To study the roles of Hoxa9 during human development we generated a transgenic H9 (hESC) line that overexpresses HoxA9 and the Enhanced Green Fluorescent Protein (EGFP), and a control H9 with a stable expression of the EGFP. The resulting H9-HoxA9-EGFP and H9-EGFP cell lines allow an efficient visualization of hESCs by fluorescent microscopy, quantification by flow cytometry and cell differentiation tracking. Both transgenic cell lines maintained the pluripotent phenotype, the ability to differentiate into all three germ layers and a normal karyotype.

Although i(17q) [i(17q)] is frequently detected in hematological malignancies, few studies have assessed its clinical role in chronic lymphocytic leukemia (CLL). We recruited a cohort of 22 CLL patients with i(17q) and described their biological characteristics, mutational status of the genes TP53 and IGHV and genomic complexity. Furthermore, we analyzed the impact of the type of cytogenetic anomaly bearing the TP53 defect on the outcome of CLL patients and compared the progression-free survival (PFS) and overall survival (OS) of i(17q) cases with those of a group of 38 CLL patients harboring other 17p aberrations. We detected IGHV somatic hypermutation in all assessed patients, and TP53 mutations were observed in 71.4% of the cases. Patients with i(17q) were more commonly associated with complex karyotypes (CK) and tended to have a poorer OS than patients with other anomalies affecting 17p13 (median OS, 44 vs 120 months, P = 0.084). Regarding chromosomal alterations, significant differences in the median OS were found among groups (P = 0.044). In conclusion, our findings provide new insights regarding i(17q) in CLL and show a subgroup with adverse prognostic features.

Native or pegylated (PEG) asparaginase (ASP) are commonly used in treatment of acute lymphoblastic leukemia (ALL), but have been scarcely compared in the same trial in adult patients. Native vs. PEG-ASP administered according to availability in each center were prospectively evaluated in adults with high-risk ALL. Ninety-one patients received native ASP and 35 PEG-ASP in induction. No significant differences were observed in complete remission, minimal residual disease levels after induction and after consolidation, disease-free survival, and overall survival. No significant differences in grades 3-4 toxicity were observed in the induction period, although a trend for higher hepatic toxicity was observed in patients receiving PEG-ASP. In this trial the type of ASP did not influence patient response and outcome.